The GY-HM600 supports an SDXC memory card which is better than most camcorders that have been available for the last year. Most video cameras that have been available for a similar time to it support an SDHC memory card. SDXC cards are SD cards but with a much higher capacity and faster processing speeds. They have a maximum capacity of 2TB (Terabytes).
An SDXC memory card is in fact the best supported memory card type amongst all latest comparable spec video cameras.
The worst supported memory card type amongst comparable types of video camera is SD.
SDHC cards are DS cards with a higher capacity of up to 32GB.